Sugar ring pucker: Difference between revisions
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==Relieving ring strain== | ==Relieving ring strain== | ||
For a 5-membered ring with perfectly tetrahedral geometry of each atom in the ring, there is some strain if the ring were planar (355 degree rotation around the ring instead of 360). To relieve the strain, one or two atoms move out of the plane. The conformation with one atom out of the plane is called envelope (endo or exo depending on whether the atom is above or below the plane). The conformation with two consecutive atoms out of the plane, one above and one below, is called twist. More than two atoms are never out of plane because the remaining three atoms always define a plane. | For a 5-membered ring with perfectly tetrahedral geometry of each atom in the ring, there is some strain if the ring were planar (355 degree rotation around the ring instead of 360). To relieve the strain, one or two atoms move out of the plane. The conformation with one atom out of the plane is called envelope (endo or exo depending on whether the atom is above or below the plane). The conformation with two consecutive atoms out of the plane, one above and one below, is called twist. More than two atoms are never out of plane because the remaining three atoms always define a plane. | ||
You can show the 5 possible planes defined by three consecutive ring atoms by clicking on the radio buttons below. In three cases, the remaining two atoms are on the same side of the plane. In two cases ("123" and "512"), carbon 4 is moved out of the plane, making this conformation a carbon 4 envelope. | |||
<jmol> | <jmol> | ||